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Title: Investigation of the anti-cancer properties of natural products and synthetic analogues with NQO2 inhibiting potential
Author: Adegbesan, Bukunola
ISNI:       0000 0004 7226 3723
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2018
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Research Background: Quinone oxidoreductase is a family of proteins consisting of the NRH quinone oxidoreductase 2 (NQO2) and the NADPH quinone oxidoreductase 1 (NQO1) enzymes which are involved in the two-electron reduction and detoxification of quinones and their derivatives. The biological function of NQO2 has not yet been elucidated but it has been shown that its genetic knockdown in hepatoblastoma cells resulted in reduction in the level of p53 while its induction in keratinocytes leads to p53 activation thus indicating that NQO2 is associated with p53 stability and prevention of its degradation. NQO2 is overexpressed in some types of cancer therefore inhibiting its enzymatic activity could potentially be used for the treatment of a variety of diseases including Alzheimer's disease and cancer. The mammalian sirtuins are implicated in numerous biological processes affecting genomic stability, cellular stress resistance, and energy metabolism. Many natural agents and synthetic analogues targeting both NQO2 and sirtuins have been used as experimental drugs in cancer prevention and treatment. Among these is Resveratrol (3,4'5-trihydroxy-trans-stilbene), a member of a group of compounds known as polyphenols which has been shown to inhibit the enzymatic activity of NQO2 by repressing its mRNA and protein levels in a dose-response relationship and activates sirtuins by mimicking caloric restriction. Aims of Research: The research aims at delineating the crosstalk between NQO2 and Sirtuins using resveratrol, sirtinol and other synthetic analogues in breast cancer and explores pathways that could be used to design novel cancer therapeutics based on the biological effects mediated by NQO2 and Sirt-1. Methods: The interrelation between Sirt-1 and NQO2 was investigated by probing for p53 and E2F1 protein levels in four different breast cancer cell lines using western blot analysis; the effect of these activators and inhibitors on cell cycle progression, mitochondrial membrane potential (MMP), NAD+/NADH ratio and reactive oxygen species (ROS) generation were determined; the potential NQO2 and/or Sirt-1 mediated regulation of p53 and E2F1 transcriptional activities was investigated using CYCE, Beclin-1 and DHFR luciferase reporter assays as well as the estimation of Beclin-1, p21 and GLS2 gene expression. Research findings and implications: The results from this study indicate that: i. Treatment of breast cancer cells with the NQO2 inhibitor and Sirt-1 activator resveratrol, the Sirt-1 inhibitor sirtinol, and the potential NQO2 inhibitors B026, B030, B031 differentially affect p53 and E2F1 transcriptional activity suggesting that Sirt-1 and NQO2 exert synergistic or antagonistic effects on the two (p53 and E2F1) main regulators of cell cycle and apoptosis in a cell type dependent manner. ii. Resveratrol, sirtinol, B026, B030 and B031 regulate cell cycle progression, ROS generation, mitochondrial membrane potential and NAD+/NADH ratio in a manner dependent on breast cancer cell lines genetic background. Differential regulation of p53 and E2F1 transcriptional activity by NQO2 and Sirt-1 governs alternative energy production pathways including glutaminolysis. All these results put together suggest that resveratrol, sirtinol, and the putative NQO2 inhibitors B026, B030 and B031could be useful tools in breast cancer therapy.
Supervisor: Stratford, Ian ; Demonacos, Constantinos Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available